netdev - [PATCH 00/13] ARM BPF jit compiler improvements

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Date:   Tue, 10 Jul 2018 13:33:40 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH 00/13] ARM BPF jit compiler improvements

Hi,

This series improves the ARM BPF JIT compiler by:
- enumerating the stack layout rather than using constants that happen
  to be multiples of four
- rejig the BPF "register" accesses to use negative numbers instead of
  positive, which could be confused with register numbers in the bpf2a32
  array.
- since we maintain the ARM FP register as a pointer to the top of our
  scratch space (or, with frame pointers enabled, a valid ARM frame
  pointer register), we can access our scratch space using FP, which is
  constant across all BPF programs, including tail-called programs.
- use immediate forms of ARM instructions where possible, rather than
  first loading the immediate into an ARM register.
- use load-with-shift instruction rather than seperate shift instruction
  followed by load
- avoid reloading index and array in the tail-call code
- use double-word load/store instructions where available

 arch/arm/net/bpf_jit_32.c | 927 +++++++++++++++++++++++-----------------------
 arch/arm/net/bpf_jit_32.h |  44 +--
 2 files changed, 493 insertions(+), 478 deletions(-)

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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